In a dioecious flowering plant, which types of pollination are prevented?

Autogamy and geitonogamy

The correct answer is Option (3)-Autogamy and geitonogamy

In dioecious flowering plants, the occurrence of both autogamy and geitonogamy is prevented. This is because dioecious plants have separate male and female flowers on different individual plants.

Autogamy, which is the process of self-pollination within the same flower, is not possible in dioecious plants because the male and female reproductive structures are located on different plants.

Similarly, geitonogamy, which is the transfer of pollen between different flowers of the same plant, is also prevented because the male and female flowers are on separate plants.

Dioecious plants rely on cross-pollination, where pollen is transferred between different plants of the same species, ensuring genetic diversity and promoting outbreeding.